On Fri, Aug 27, 2010 at 06:17:36PM +0200, Artem.Bityutskiy@xxxxxxxxx wrote:
> I need to look more. But so far I do not really understand what could make kthread_stop() wait
> forever. I looked into the code, and thought may be barriers are missing there, but I is unlikely
> this generic type of code would have bugs.
Hm, is the way you go to sleep in the writeback thread safe? Surely
there's a race like:
while(!kthread_should_stop()) {
kthread_stop():
kthread->should_stop = 1;
wake_up_process(k);
wait_for_completion(&kthread->exited);
/* oops, lose the wake_up here: */
set_current_state(TASK_INTERRUPTIBLE);
...
/* sleep forever: */
schedule();
Maybe the following?
--b.
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7d9d06b..ea76550 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -808,7 +808,7 @@ int bdi_writeback_thread(void *data)
wb->last_active = jiffies;
set_current_state(TASK_INTERRUPTIBLE);
- if (!list_empty(&bdi->work_list)) {
+ if (!list_empty(&bdi->work_list) || kthread_should_stop()) {
__set_current_state(TASK_RUNNING);
continue;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
